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''Saccharomyces'' species and individual strains have a wide range of tolerance to low pH and lactic/acetic acid concentrations, which have been identified as stressors for yeast fermentation. For ideal fermentation conditions for ''S. cerevisiae'', lactic acid should not exceed 0.8%, acetic acid should not exceed 0.5%, and wort should not fall below 4.0 pH. This obviously presents a challenge to brewers when [[Sour Worting]] or [[Packaging|naturally carbonating with yeast]] for sour beers <ref name="rogers2016">[http://www.sciencedirect.com/science/article/pii/S0740002016301605 Terminal acidic shock inhibits sour beer bottle conditioning by Saccharomyces cerevisiae. Cody M. Rogers, Devon Veatch, Adam Covey, Caleb Staton, Matthew L. Bochman. 2016.]</ref>.
Yeast that fails to bottle condition sour beer may not be due to death of the cells. Rogers et al. <ref name="rogers2016"></ref> published a study that found that yeast used to bottle condition a sour beer at [http://uplandbeer.com/ Upland Brewing Co.] was still ~80% viable after two weeks, but the surviving cells were small and unbudded, indicating that they ceased growing and entered the stationary phase <ref name="rogers2016"></ref>.